The present invention relates to a rotary sanding apparatus.
The present invention, more particularly, relates to a rotary sanding apparatus, that can be driven by an electric motor to perform a sanding operation.. The apparatus comprises a circular support plate having a hub structure extending from its rear face for mounting the apparatus on a portable drilling machine, or similar rotary power device. A resilient deformable pad is secured to the front face of the support plate to form a mounting surface for a circular abrasive disk.
The resilient deformable pad is formed of a foamed plastic material, e.g. polyurethane foam, to a thickness of about one inch, whereby the abrasive disk can conform to irregular contours on the work piece. The aim is to facilitate sanding operations on non-flat work surfaces, i.e. surfaces having concave or convex contours.
The use of foamed plastic pads in rotary sanding apparatus is already known. U.S. Pat. No. 3,924,362, issued to H. McAleer on Dec. 9, 1975, shows a foamed pad that includes a soft foam core, and a somewhat harder (or more rigid) outer foam layer bonded to the front face of the foam core. As shown in FIG. 2 of the McAleer patent drawings, the outer foam layer extends around the outer edge of the foam core to form an edge covering. McAleer indicates that the outer foam layer is semi-rigid and relatively tough, to provide better wear and durability than the soft foam core alone. McAleer further indicates that the durability is achieved without sacrificing overall flexibility or resilience, e.g., see column 3, line 20, of the patent. McAleer also indicates that the hard outer foam layer assists in minimizing high speed distortion of the pad so as to permit the use of a larger diameter pad for a given rotational speed.
The present invention seeks to provide a foam pad reinforcing action by a different mechanism than that used by McAleer.